AB1847 ANTI-MYELOPEROXIDASE ANTIBODY-POSITIVE GRANULOMATOSIS WITH POLYANGIITIS MIMICKING MUCOSAL LEISHMANIASIS: A RARE CASE REPORT
Authors: I. Nogueira, M. Montenegro, V. Alcantara, T. N. Albuquerque Gomes Nogueira
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Granulomatosis with polyangiitis (GPA) features necrotizing granulomatous inflammation of the upper and lower respiratory tracts, with vasculitis of small- and medium- sized vessels [1]. Anti-proteinase 3 antibodies (PR3-ANCA) are found in the majority of cases, yet anti-myeloperoxidase (MPO-ANCA) may be identified in approximately 10% of patients with GPA [2, 3]. One of the differential diagnoses is mucosal leishmaniasis, especially in patients from endemic regions. Atypical presentations of GPA may delay diagnosis. <h3>Objectives</h3> To report a case of a female patient previously diagnosed with and treated for mucosal leishmaniasis due to upper respiratory tract lesions. As the symptoms returned alongside arthritis, further investigation concluded to a diagnosis of anti-myeloperoxidase-positive GPA. <h3>Methods</h3> Case report and discussion. <h3>Results</h3> A 51-year-old woman from Brazil presented in 2021 with epistaxis and joint pain. The patient reported a prior history of recurring bilateral epistaxis and maxillary pain since 2008. At that time, she had a wide nasal septal perforation. CT scan of the sinuses showed maxillary and ethmoidal sinusopathy. A nasal biopsy showed epithelioid granulomas without amastigotes, but the patient had a 25mm Montenegro skin test (strongly positive). Syphilis, hepatitis B, hepatitis C and HIV screenings and acid-fast bacilli smear were negatives. As Brazil is an endemic region for leishmaniasis, a presumptive diagnosis of mucosal leishmaniasis was made and the patient was appropriately treated. In 2016, she was lost to follow-up. In 2021, she returned with fever, epistaxis, important unspecified weight loss and arthralgia with edema in ankles, distal interphalangeal joints, metacarpophalangeal joints and wrists. Blood screening revealed an RCP of 9.5 and an ESR of 28. Urine tests were normal. A thoracic CT scan showed multiple lung nodular formations, including a subpleural nodule in the anterior lower right lobe, with a size of 3.8 x 3.1 x 2.9 cm. Lung histopathology revealed foci of poorly formed, non-necrotic granulomas in centrilobular parenchyma and angiitis in small-caliber arteries (image 1). Autoimmune screening revealed positive MPO-ANCA superior to 1/80 and negative c-ANCA, rheumatoid factor and anti-CCP. Thus, a diagnosis of GPA was made, and oral methotrexate 20mg weekly was started. Improvement of arthritis could be observed in four weeks. <h3>Conclusion</h3> GPA may present upper respiratory tract symptoms, and is considered a differential diagnosis for mucosal leishmaniasis [4]. Recurrence of the symptoms in a patient treated for mucosal leishmaniasis should prone further investigation for other conditions. The renal system was spared in our patient, however nasal septal involvement, prominent sinusopathy, joint symptoms and pulmonary typical findings strongly favored the hypothesis of GPA. A positive MPO-ANCA and good therapeutic response following methotrexate strengthened the certainty of the diagnosis. Physicians should be aware of GPA as a differential diagnosis for mucosal leishmaniasis and recognize its MPO-ANCA-positive presentation. <h3>References</h3> [1] Comarmond C, Cacoub P. Granulomatosis with polyangiitis (Wegener): clinical aspects and treatment. Autoimmunity reviews. 2014 Nov 1;13(11):1121-5. [2] Puéchal X. Granulomatosis with polyangiitis (Wegener's). Joint bone spine. 2020 Dec 1;87(6):572-8. [3] Bosch X, Guilabert A, Font J. Antineutrophil cytoplasmic antibodies. The Lancet. 2006 Jul 29;368(9533):404-18 [4] Rojas-Jaimes J, Hugo Rojas Figueroa V, Corcuera-Ciudad R, Arenas J, García-Reynoso J. Wegener's granulomatosis and differential diagnosis of mucosal leishmaniasis. Clinical Case Reports. 2021 Jun;9(6):e04280 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.